Injection nozzle for an ink jet printer

ABSTRACT

An injection nozzle for an ink jet printer comprises a fine pipe for feeding ink therethrough onto a separately positioned paper under the control of an electric field, the one end of the pipe being faced toward the paper and being obliquely cut away through the axis thereof and having a sharp lead point to concentrate the electric field further cut from the sides of the cutting plane of the oblique cut.

United States Patent Kojima 1 May 27, 1975 INJECTION NOZZLE FOR AN INKJET 3.438.059 4/1969 Highley U 346/140 PRINTER 3.466.659 9/1969 AS6011346/140 Primary Examiner-Joseph W. Hartary Attorney, Agent, orFirm-Oblon. Fisher. Spivak. McClelland & Maier ABSTRACT An injectionnozzle for an ink jet printer comprises a fine pipe for feeding inktherethrough onto a separately positioned paper under the control of anelectric field, the one end of the pipe being faced toward the paper andbeing obliquely cut away through the axis thereof and having a sharplead point to concentrate the electric field further cut from the sidesof the cutting plane of the oblique cut.

4 Claims, 6 Drawing Figures Patented May 27, 1975 3,886,565

(PRIOR ART) (PRIOR ART) INJECTION NOZZLE FOR AN INK JET PRINTERBACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention relates generally to an ink jet printer and, moreparticularly, to an improved ink injection nozzle for an ink jetprinter.

2. Description of the Prior Art:

Ink jet printers are usually designated to have various features such assimple construction, quiet operation, and capability of printing onordinary lower cost paper which offers many applications includingfacsimile apparatus.

FIG. 1 shows a schematic diagram of a conventional ink jet facsimileapparatus wherein an ink injection nozzle 4 is inserted in a metalholder 3 secured at the bottom of an ink vessel 1 through an insulatedpacking ring 2. The metal holder 3 is connected to a conductor 9 whichis supplied with a high voltage DC. bias and video signal. The inkvessel 1 is mounted on a base plate 5 which is movable along a lineparallel to the longitudinal axis of a cylindrical drum 8, positionedalong one side thereof, by a driving motor, not shown, at apredetermined mainscanning rate, the cylindrical metal drum 8 beingconnected to a ground potential and rotated by a driving motor, also notshown, at a predetermined sub-scanning rate. Ordinary lower cost paper 7is wound on the surface of the drum 8.

In this conventional, or prior art, apparatus, ink of a relatively highoil concentration is preferably used. The DC. bias and video signal forexample, are about 2K. V and 0.7K. V., respectively, and the gap betweenthe pointed end of the ink injection nozzle 4 and the drum 8 isgenerally between I mm and 4 mm.

The nozzle 4 has an appropriate outer diameter of 0.4 mm, and anapproximate inner diameter of 0.2 mm and is tapered at one end, but thepointed end thereof is cut to be perpendicular to the axis of the nozzle4. Therefore, the frequency response of the ink droplet is limitedwithin 2 KHz because of the variations of the ink meniscus formed, aswill be described hereinafter.

The ink meniscus at the end of the conventional ink injection nozzle 4is varied as shown in FIG. 2. When the DC. bias and the video signal arenot supplied to the conductor 9, or only the DC. bias is suppliedthereto, the ink flows from the vessel 1 to the nozzle 4 through theholder 3 and a meniscus 10 thereof at the pointed end of nozzle 4, asshown in FIG. 2a, is formed by the surface tension effect.

But, when the voltage supplied to the conductor 9 is higher than thepredetermined level, the ink is attracted by the electric field betweenthe pointed end of nozzle 4 and the drum 8 so that ink droplets II, asshown in FIG. 2b, are shot toward the paper 7 wound on the surface ofthe drum 8.

After shooting such ink droplets, an ink meniscus 12, as shown in FIG.20, is formed. This process of ink meniscus formation is repeated andprinting of various patterns on the paper 7 is made in accordance withthe video signal.

The significant variation of the ink meniscus, as shown in FIG. 2,however, does not only result in limited frequency response thereof, butalso brings about an edge effect phenomenon on the printed patterns onaccount of the ink being initially injected in the form of lumps at eachinitial shooting time.

SUMMARY OF THE INVENTION Accordingly, it is one object of the presentinvention to provide a new and improved unique injection nozzle for anink jet printer.

It is another object of this invention to provide an im' provedinjection nozzle for an ink jet printer which is capable of making thefrequency response of the ink droplets more quick.

It is yet another object of this invention to provide an improvedinjection nozzle for an ink jet printer which will produce printedpatterns of b tter quality.

In summary, according to the present invention, the foregoing objectsand others are achieved by a novel injection nozzle for an ink jetprinter which comprises a fine pipe for feeding ink therethrough on aseparately positioned paper under the function of an electric field, thepipe being obliquely cut away to the axis thereof to form a leading edgefacing the paper, and both sides of this edge being further cut away toform a sharply pointed end for concentrating the electric field.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features andattendant advantages of the present invention will be more fullyappreciated as the same becomes better understood from the followingdetailed description of the present invention when considered inconnection with the accompanying drawings, in which:

FIG. 1 illustrates a schematic diagram of a conventional ink jetprinter, previously described;

FIG. 2 shows the ink meniscus being formed in the operation of theconventional injection nozzle, as previously described;

FIG. 3 shows a top view of a preferred embodiment of an ink injectionnozzle formed according to the present invention; and

FIG. 4 shows a side view of the embodiment illustrated in FIG. 3 and theink meniscus being formed therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS.3 and 4, an ink injection nozzle generally designated by referencenumeral 30 for an ink jet printer is formed from a fine metal pipe 20having the usual axial channel for feeding ink therethrough onto aseparately positioned paper under the function or control of an electricfield, in the usual manner, as previously discussed.

The pipe 20 is tapered near one end and is then further obliquely cutaway along one plane toward and through the longitudinal axis 25 thereofto form a leading edge 21. The cutting angle 6 which is formed betweenthe oblique plane 22 and the longitudinal axis 25 is in a range ofdegrees from 30 to 60. Both of the lateral edges 23 and 24 of theleading edge 21 formed on either side thereof by the oblique plane 22are further cut away to form a sharply pointed end 26. The pointed end26, however, may have a radius of curvature of an ink droplet producedby the attraction of the electric field.

When the injection nozzle 30 is adapted for conventional facsimileapparatus, as shown in FIG. I, under the same conditions describedabove, the frequency response of ink droplets results in 4 KHz or moreand printed patterns of better quality are thus obtained. It

may be due to the fact that the wide variations in ink meniscus becauseof the surface tension effect are not easily produced. whether shootingink droplets or not, that the edge effect phenomenon of printed patternsis significantly reduced.

According to the present invention, the nozzle should be formed from ametal pipe preferably having an outer diameter in the range of between0.4 mm and 0.7 mm and an inner diameter in the range of between 0.2 mmand 0.4 mm. The gap between the pointed end of the ink injection nozzleand the drum preferably should be generally between 1 mm and 4 mm.

Tests with a nozzle formed from a metal pipe having an outer diameter of0.4 mm and an inner diameter of 0.2 mm provided highly satisfactoryresults.

In the case of another embodiment using the same injection nozzle,except utilizing a metal pipe having an outer diameter 0.55 mm, and aninner diameter of 0.3 mm, substantially the same result was achieved.

Obviously, numerous additional modifications and variations of thepresent invention are possible in light of the above teachings. It istherefore to be understood that within the scope of the appended claims,the invention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. An injection nozzle for an ink jet printer. comprising a fine pipehaving a longitudinal channel for feeding ink therethrough onto aseparately positioned paper under the control of an electric field, oneend of said pipe being tapered and cut away along an oblique planetoward and through the axis thereof to form a leading edge facing saidpaper, and both sides of said leading edge being further cut away toform a sharply pointed end for concentrating said electric field.

2. An injection nozzle according to claim 1, wherein said pipe is madeof metal and said ink has an oily character.

3. An injection nozzle according to claim I, wherein the outer diameterof said pipe is on the order of between 0.4 mm and 0.7 mm, the innerdiameter is on the order of between 0.2 mm and 0.4 mm, and the gapbetween said pointed end and said paper is approximately between 1.0 and4.0 mm.

4. An injection nozzle according to claim 1, wherein the cutting angleof said pipe to the axis thereof when obliquely cut is in the range offrom 30 to 60.

1. An injection nozzle for an ink jet printer, comprising a fine pipehaving a longitudinal channel for feeding ink therethrough onto aseparately positioned paper under the control of an electric field, oneend of said pipe being tapered and cut away along an oblique planetoward and through the axis thereof to form a leading edge facing saidpaper, and both sides of said leading edge being further cut away toform a sharply pointed end for concentrating said electric field.
 2. Aninjection nozzle according to claim 1, wherein said pipe is made ofmetal and said ink has an oily character.
 3. An injection nozzleaccording to claim 1, wherein the outer diameter of said pipe is on theorder of between 0.4 mm and 0.7 mm, the inner diameter is on the orderof between 0.2 mm and 0.4 mm, and the gap between said pointed end andsaid paper is approximately between 1.0 and 4.0 mm.
 4. An injectionnozzle according to claim 1, wherein the cutting angle of said pipe tothe axis thereof when obliquely cut is in the range of from 30* to 60*.